Functionalisation of gas diffusion layers via remote plasma deposition: Tailoring surface morphology for enhanced fuel cell performance

In this study, we explore the innovative synthesis and properties of “rose petal-like” hydrophobic thin films for gas diffusion layers (GDLs) in proton exchange membrane fuel cells (PEMFCs), using a conformal and non-line-of-sight remote plasma deposition process of perfluorinated materials. The hydrophilization of carbon based GDL to optimise the water management in fuel cells is a crucial aspect studied in the literature and in industries. The most common hydrophobic agent is polytetrafluoroethylene (PTFE), which is typically applied by immersing the GDL in a PTFE emulsion followed by a thermal treatment or by spray-coating. Here, we propose an advanced technique enabling the room temperature deposition of hydrophobic films with precise control over the surface morphology and the coating thickness, allowing for the creation of tailored nanostructures enhancing the water management in GDL. By adjusting the deposition parameters, we achieved the formation of rose petal-like nanostructures at a substrate temperature of 20 °C, which significantly improved the hydrophobicity of the GDL while maintaining moderate electrical conductivity. These structures exhibited superior performance in fuel cell testing, preventing water flooding. In contrast, a thicker and more uniform coating formed at 40 °C resulted in reduced conductivity and poorer fuel cell performance due to excessive insulation. The remote plasma deposition process offers significant advantages over traditional methods, ensuring uniform, non-line-of-sight coatings with scalability for industrial applications. This approach presents a feasible approach for developing high-performance GDLs that enhance PEMFC efficiency and durability, with potential implications for a range of clean energy technologies. • Innovative Remote Plasma Deposition of perfluoronated structures. • Rose petal-like nanostructures significantly improve the hydrophobicity. • Nanostructure tailoring for improved water management in fuel cells. • Scalable and Uniform Coating Process of perfluoronated nanostructures.